6-Fluoro-2-Methylbenzo[d]thiazol-5-yl Compounds

ABSTRACT

The present invention provides a compound of Formula I: 
     
       
         
         
             
             
         
       
         
         
           
             wherein 
             R is hydrogen or methyl; and 
             Z is: 
           
         
       
    
     
       
         
         
             
             
         
       
     
     or a pharmaceutically acceptable salt thereof, and the use of compounds of Formula I for treating neurodegenerative diseases, such as Alzheimer&#39;s disease.

The present invention relates to novel6-fluoro-2-methylbenzo[d]thiazol-5-yl compounds, to pharmaceuticalcompositions comprising the compounds, to methods of using the compoundsto treat neurodegenerative disorders such as Alzheimer's disease (AD),and to intermediates and processes useful in the synthesis of thecompounds.

The present invention is in the field of treatment of AD, progressivesupranuclear palsy (PSP), and other diseases and disorders involvingtau-mediated neurodegeneration, known collectively as tauopathies.

AD is a devastating neurodegenerative disorder that affects millions ofpatients worldwide. In view of the currently approved agents on themarket which afford only transient symptomatic benefits to the patient,there is a significant unmet need in the treatment of AD.

The oligomerization of the microtubule-associated protein tau intofilamentous structures such as paired helical filaments (PHFs) andstraight or twisted filaments, which give rise to neurofibrillarytangles (NFTs) and neuropil threads (NTs), is one of the definingpathological features of AD and other tauopathies. The number of NFTs inthe brains of individuals with AD has been found to correlate closelywith the severity of the disease, suggesting tau has a key role inneuronal dysfunction and neurodegeneration (Nelson et al., JNeuropatholExp Neurol., 71(5), 362-381(2012)). Tau pathology has beenshown to correlate with disease duration in PSP in that cases with amore aggressive disease course have a higher tau burden than cases witha slower progression. (Williams et al., Brain, 130, 1566-76 (2007)).

Past studies (Yuzwa et al., Nat Chem Biol, 4(8), 483-490 (2008)) supportthe therapeutic potential of O-GlcNAcase (OGA) inhibitors to limit tauhyperphosphorylation, and aggregation into pathological tau, for thetreatment of AD and related tau-mediated neurodegeneration disorders.More recently, the OGA inhibitor Thiamet-G has been linked to slowingmotor neuron loss in the JNPL3 tau mouse model (Yuzwa et al., Nat ChemBiol, 8, 393-399 (2012)), and to a reduction in tau pathology anddystrophic neurites in the Tg4510 tau mouse model (Graham et al.,Neuropharmacology, 79, 307-313 (2014)). Accordingly, OGA inhibitors arerecognized as a viable therapeutic approach to reduce the accumulationof hyperphosphorylated, pathological forms of tau.

US 2017/0298082 discloses certain glycosidase inhibitors useful intreating tauopathies such as AD. WO 2018/109198 A1 and WO 2018/109202 A1disclose certain OGA inhibitors useful for treating tauopathies, such asAD and PSP.

OGA inhibitors that are brain penetrant are desired to providetreatments for tau-mediated neurodegeneration disorders, such as AD andPSP. The present invention provides certain novel compounds that arepotent inhibitors of OGA. In addition, the present invention providescertain novel compounds that are potent inhibitors of OGA with thepotential to be sufficiently brain penetrant to effectively treattauopathies, such as AD and PSP.

Accordingly, the present invention provides a compound of Formula I:

wherein

R is hydrogen or methyl; and

Z is:

or a pharmaceutically acceptable salt thereof.

The present invention also provides a compound of Formula II:

wherein X is N or CH,or a pharmaceutically acceptable salt thereof.

The present invention also provides a method of treating Alzheimer'sdisease in a patient in need of such treatment, comprising administeringto the patient an effective amount of a compound of Formula I or II, ora pharmaceutically acceptable salt thereof.

The present invention further provides a method of preventing theprogression of mild cognitive impairment to Alzheimer's disease in apatient in need of such treatment, comprising administering to thepatient an effective amount of a compound of Formula I or II, or apharmaceutically acceptable salt thereof.

The present invention also provides a method of treating progressivesupranuclear palsy in a patient in need of such treatment, comprisingadministering to the patient an effective amount of a compound ofFormula I or II, or a pharmaceutically acceptable salt thereof. Thepresent invention also provides a method of treating tau-mediatedneurodegenerative disorders in a patient, comprising administering to apatient in need of such treatment an effective amount of a compound ofFormula I or II, or a pharmaceutically acceptable salt thereof.

Furthermore, this invention provides a compound of Formula I or II, or apharmaceutically acceptable salt thereof for use in therapy, inparticular for use in treating Alzheimer's disease or for use inpreventing the progression of mild cognitive impairment to Alzheimer'sdisease. In addition, this invention provides a compound of Formula I orII, or a pharmaceutically acceptable salt thereof for use in treatingprogressive supranuclear palsy. The invention also provides a compoundof Formula I or II, or a pharmaceutically acceptable salt thereof foruse in treating tau-mediated neurodegenerative disorders.

Even furthermore, this invention provides the use of a compound ofFormula I or II, or a pharmaceutically acceptable salt thereof, for themanufacture of a medicament for treating Alzheimer's disease or forpreventing the progression of mild cognitive impairment to Alzheimer'sdisease. In addition, this invention provides the use of a compound ofFormula I or II, or a pharmaceutically acceptable salt thereof, for themanufacture of a medicament for treating progressive supranuclear palsy.The invention also provides the use of a compound of Formula I or II, ora pharmaceutically acceptable salt thereof, for the manufacture of amedicament for treating tau-mediated neurodegenerative disorders.

The invention further provides a pharmaceutical composition, comprisinga compound of Formula I or II, or a pharmaceutically acceptable saltthereof, with one or more pharmaceutically acceptable carriers,diluents, or excipients. The invention further provides a process forpreparing a pharmaceutical composition, comprising admixing a compoundof Formula I or II, or a pharmaceutically acceptable salt thereof, withone or more pharmaceutically acceptable carriers, diluents, orexcipients.

Mild cognitive impairment has been defined as a potential prodromalphase of dementia associated with Alzheimer's disease based on clinicalpresentation and on progression of patients exhibiting mild cognitiveimpairment to Alzheimer's disease over time. The term “preventing theprogression of mild cognitive impairment to Alzheimer's disease”includes restraining, slowing, stopping, or reversing the progression ofmild cognitive impairment to Alzheimer's disease in a patient.

As used herein, the terms “treating” or “to treat” includes restraining,slowing, stopping, or reversing the progression or severity of anexisting symptom or disorder.

As used herein, the term “patient” refers to a human.

As used herein, the term “effective amount” refers to the amount or doseof compound of the invention, or a pharmaceutically acceptable saltthereof which, upon single or multiple dose administration to thepatient, provides the desired effect in the patient under diagnosis ortreatment.

An effective amount can be determined by one skilled in the art by theuse of known techniques and by observing results obtained underanalogous circumstances. In determining the effective amount for apatient, a number of factors are considered, including, but not limitedto: the species of patient; its size, age, and general health; thespecific disease or disorder involved; the degree of or involvement orthe severity of the disease or disorder; the response of the individualpatient; the particular compound administered; the mode ofadministration; the bioavailability characteristics of the preparationadministered; the dose regimen selected; the use of concomitantmedication; and other relevant circumstances. The compounds of thepresent invention are effective at a dosage per day that falls withinthe range of about 0.1 to about 15 mg/kg of body weight.

The compounds of the present invention are formulated as pharmaceuticalcompositions administered by any route which makes the compoundbioavailable. Preferably, such compositions are for oral administration.Such pharmaceutical compositions and processes for preparing same arewell known in the art (See, e.g., Remington: The Science and Practice ofPharmacy, L. V. Allen, Editor, 22^(nd) Edition, Pharmaceutical Press,2012).

The compounds of Formula I and the pharmaceutically acceptable saltsthereof are particularly useful in the treatment methods of theinvention, with certain configurations being preferred. The followinglist of compounds of the present invention describe such configurations.It will be understood that these preferences are applicable both to thetreatment methods and to the compounds of the invention.

Compounds of the present invention include:

wherein X is N or CH;and pharmaceutically acceptable salts thereof.

The compound of Formula I wherein the methyl and oxygen substituents onthe pyrrolidine ring are in the cis or trans configuration, orpharmaceutically acceptable salt thereof, are included within the scopeof the invention, with the cis configuration being preferred. Forexample, one of ordinary skill in the art will appreciate that themethyl at position 5 on the pyrrolidine ring is in the cis configurationrelative to the oxygen at position 3 as shown in Scheme A below:

In addition, one of ordinary skill in the art will appreciate that themethyl at position 5 on the pyrrolidine ring is in the transconfiguration relative to the oxygen at position 3 as shown in Scheme Bbelow:

It is preferred that when R is methyl, the methyl group may be in the(R)-configuration or in the (S)-configuration, and it is especiallypreferred that when R is methyl, the methyl group is in the(S)-configuration.

Although the present invention contemplates all individual enantiomersand diasteromers, as well as mixtures of the enantiomers of saidcompounds, including racemates, the compound of Formula Ia andpharmaceutically acceptable salts thereof is preferred.

Individual enantiomers may be separated or resolved by one of ordinaryskill in the art at any convenient point in the synthesis of compoundsof the invention, by methods such as selective crystallizationtechniques, chiral chromatography (See for example, J. Jacques, et al.,“Enantiomers, Racemates, and Resolutions”, John Wiley and Sons, Inc.,1981, and E. L. Eliel and S. H. Wilen, “Stereochemistry of OrganicCompounds”, Wiley-Interscience, 1994), or supercritical fluidchromatography (SFC) (See for example, T. A. Berger; “SupercriticalFluid Chromatography Primer,” Agilent Technologies, July 2015).

A pharmaceutically acceptable salt of the compounds of the invention canbe formed, for example, by reaction of an appropriate free base of acompound of the invention and an appropriate pharmaceutically acceptableacid in a suitable solvent under standard conditions well known in theart. See, for example, Gould, P. L., “Salt selection for basic drugs,”International Journal of Pharmaceutics, 33: 201-217 (1986); Bastin, R.J., et al. “Salt Selection and Optimization Procedures forPharmaceutical New Chemical Entities,” Organic Process Research andDevelopment, 4: 427-435 (2000); and Berge, S. M., et al.,“Pharmaceutical Salts,” Journal of Pharmaceutical Sciences, 66: 1-19,(1977).

The compounds of the present invention, or salts thereof, may beprepared by a variety of procedures known to one of ordinary skill inthe art, some of which are illustrated in the schemes, preparations, andexamples below. The products of each step in the schemes below can berecovered by conventional methods well known in the art, includingextraction, evaporation, precipitation, chromatography, filtration,trituration, and crystallization. In the schemes below, all substituentsunless otherwise indicated, are as previously defined. The reagents andstarting materials are readily available to one of ordinary skill in theart. Without limiting the scope of the invention, the following schemes,preparations, and examples are provided to further illustrate theinvention. In addition, one of ordinary skill in the art appreciatesthat compounds of Formula I may be prepared by using starting materialor intermediate with the corresponding desired stereochemicalconfiguration which can be prepared by one of skill in the art.

Certain abbreviations are defined as follows: “ACN” refers toacetonitrile; “Ac” refers to acetyl; “AcOH” refers to acetic acid;“Ac₂O” refers to acetic anhydride; “BOC” refers to tert-butoxycarbonyl;“CBz” refers to carbonylbenzyloxy; “DCM” refers to methylene chloride ordichloromethane; “DIPEA” refers to diisopropylethylamine; “DMEA” refersto dimethylethylamine; “DMF” refers to N,N-dimethylformamide; “DMSO”refers to dimethyl sulfoxide; “dppf” refers todiphenylphosphinoferrocene; “EDTA” refers to ethylenediaminetetraaceticacid; “ES/MS” refers to Electrospray Mass Spectrometry; “EtOAc” refersto ethyl acetate; “EtOH” refers to ethanol or ethyl alcohol; “h” refersto hour or hours; “IPA” refers to isopropanol or isopropyl alcohol;“JohnPhos” refers to 2-(di-tert-butylphosphino)biphenyl; “KO-t-Bu”refers to potassium-tert-butoxide; “Me” refers to methyl; “min” refersto minute or minutes; “MTBE”: refers to methyl tert-butyl ether; “NADP”refers to β-nicotinamide adenine dinucleotide phosphate disodium salt;“NaO-t-Bu” refers to sodium-tert-butoxide; “OAc” refers to acetate oracetoxy; “RT” refers to room temperature; “TEA” refers to triethylamine;“TFA” refers to trifluoroacetic acid; “THF” refers to tetrahydrofuran;“TMEDA” refers to tetramethylethylenediamine; “Tris” refers totris(hydroxymethyl)aminomethane or2-amino-2-(hydroxymethyl)propane-1,3-diol; “[α]_(D) ²⁰” refers tospecific optical rotation at 20° C. and 589 nm, wherein c is theconcentration in g/mL.

Scheme 1 illustrates the synthesis of the compounds of Formula II. InScheme 1, step A, the pyrrolo-nitrogen of the appropriate2-chloro-6,7-dihydro-5H-pyrrolopyrimidine hydrochloride (X═N) or2-chloro-6,7-dihydro-5H-pyrrolopyridine hydrochloride (X═CH) may beacylated under a wide variety of acylating agents well known to theskilled artisan. For example, about 1 equivalent of2-chloro-6,7-dihydro-5H-pyrrolo[3,4-d]pyrimidine hydrochloride (X═N) or2-chloro-6,7-dihydro-5H-pyrrolo[3,4-b]pyridine hydrochloride (X ═CH) maybe dissolved in an appropriate organic solvent, such as DCM, about 4equivalents of a suitable non-nucleophilic base, such as TEA, pyridine,or DIPEA, may be added, and the mixture may be treated dropwise with theaddition of about 1.1 equivalents of acetyl chloride for about 15 to 20h at RT. The resulting reaction product may be isolated by techniqueswell known in the art, such as extraction and chromatography. Forexample, the acylation reaction may be quenched with a suitable mildaqueous base, such as NaHCO₃, Cs₂CO₃, or KHCO₃, the resulting biphasicmay be extracted with a suitable organic solvent, such as DCM, and thecombined organic extracts may be washed sequentially with water,saturated aqueous NaCl, dried over a suitable drying agent, such asNa₂SO₄ or MgSO₄, filtered, and the filtrate may be concentrated underreduced pressure. The resulting residue may be purified by flashchromatography over silica, using a suitable mixture of polar andnon-polar organic solvents, such as EtOAc or acetone in hexanes, toobtain the desired acylated product of Scheme 1, step A.

In Scheme 1, step B, nucleophilic aromatic substitution with anappropriately N-protected commercially available hydroxypyrrolidine iswell known in the art. The skilled artisan will recognize that a widearray of nucleophilically-stable N-protecting groups may be used, suchas Boc, CBz, benzyl, or methyl, as needed for ease of removal. Forexample, about 1 equivalent of the appropriately N-protected4-hydroxy-2-methylpyrrolidine may be treated with about 2 equivalents ofa suitable strong base, such as NaH, KO-t-Bu, or NaO-t-Bu, in ansuitable polar solvent, such as THF, DMF, 1,4-dioxane, or DMSO, at about0° C. to about RT. About 1.2 equivalents of the desired acylated productof Scheme 1, step A, may be added at about 0° C. to about RT, and theresulting mixture may be stirred at about RT for about 12-24 h. Theresulting reaction product may be isolated by techniques well known inthe art, such as extraction and chromatography. For example, thereaction mixture may be diluted with water, extracted with anappropriate organic solvent, such as DCM or EtOAc, and the combinedorganic extracts may be washed sequentially with water, saturatedaqueous NaCl, dried over a suitable drying agent, such as Na₂SO₄ orMgSO₄, filtered, and the filtrate may be concentrated under reducedpressure. The resulting residue may be purified by flash chromatographyover silica, using a suitable mixture of polar and non-polar organicsolvents, such as EtOAc or acetone in hexanes, to obtain the desiredproduct of Scheme 1, step B. The skilled artisan will recognize thatdifferent isomers (e.g., cis- or trans-) of the commercially availablehydroxypyrrolidine will give different isomers of the product of Scheme1, step B.

In Scheme 1, step C, the skilled artisan will recognize the removal ofthe protecting group may be accomplished under an array of conditionswell known in the art. For example, wherein PG=BOC, the product ofScheme 1, step B may be dissolved in a suitable organic solvent, such asDCM, and treated with an appropriate acid, such as HCl dissolved in anorganic solvent (e.g., Et₂O, 1,4-dioxane), or TFA, and the resultingreaction mixture may be stirred at about RT to about 80° C. from about30 min to 8 h. The resulting reaction product may be isolated bytechniques well known in the art, such as evaporation. For example, thereaction mixture may be subjected to concentration under reducedpressure to obtain the HCl salt of the product of Scheme 1, step C.

In Scheme 1, step D, N—C bond formation may be accomplished under avariety of methods well known in the art, including nucleophilicdisplacement of an alkyl halide, transition-metal catalysis, or underreductive amination conditions. For example, about 1 equivalent of anappropriately substituted aldehyde, such as6-fluoro-2-methyl-1,3-benzothiazole-5-carbaldehyde and about 1equivalent of the deprotected pyrrolidine hydrochloride (the product ofScheme 1, step C) may be dissolved in a suitable organic solvent, suchas DCM, and the resulting solution may be treated with about 2.5-2.75equivalents of a non-nucleophilic base, such as DIPEA or TEA for about30 min to about 1 h. About 3 equivalents of a suitable borohydridereducing agent, such as sodium borohydride, sodiumtri(acetoxy)borohydride, or sodium cyanoborohydride, may be added, andthe resulting mixture may be stirred at about RT for about 12 to 24 h.The resulting reaction product may be isolated by techniques well knownin the art, such as extraction and column chromatography. For example,the reaction mixture may be quenched slowly with a saturated aqueousmild basic solution, such as NaHCO₃. The resulting mixture may beextracted with a suitable organic solvent, such as DCM or EtOAc, and thecombined organic extracts may be washed sequentially with water,saturated aqueous NaCl, dried over a suitable drying agent, such asNa₂SO₄ or MgSO₄, filtered, and the filtrate may be concentrated underreduced pressure. The resulting residue may be purified by flashchromatography over silica, using a suitable mixture of polar andnon-polar organic solvents, such as EtOAc or acetone in hexanes, ormethanol in DCM or EtOAc, to obtain the compound of Formula II.

Scheme 2 illustrates the preparation of the requisite6-fluoro-2-methyl-1,3-benzothiazole-5-carbaldehyde. In Scheme 2, step A,the skilled artisan will recognize that 5-bromo-2,4-difluoroaniline maybe acylated by treatment with a suitable acylating reagent, such as Ac₂Oor AcCl, at RT and heated to about 60° C., to obtain the acylatedaniline. For example, about 1 equivalent of 5-bromo-2,4-difluoroanilinemay be added to about 11 equivalents of Ac₂O and the resulting mixturemay be heated to about 60° C. with stirring for about 10 min. Theresulting mixture may be concentrated under reduced pressure, agitatedin heptane, and the resulting solid collected by filtration to obtainN-(5-bromo-2,4-difluoro-phenyl)acetamide, the product of Scheme 2, stepA.

In Scheme 2, step B, the amide may be converted to the thioamide under avariety of conditions well known in the art, such as with elementalsulfur, Lawesson's Reagent, or ammonium phosphorodithioate, in asuitable organic solvent. More specifically, about 1 equivalent ofN-(5-bromo-2,4,-difluoro-phenyl)acetamide may be treated with about 0.5equivalents ofpyridin-1-ium-1-yl-[pyridin-1-ium-1-yl(sulfido)phosphinothioyl]sulfanyl-sulfido-thioxo-phosphane(see, for example, J. Org. Chem. 2011, 76, 1546-1553) in ACN and stirredat 85° C. overnight. The reaction mixture may be concentrated underreduced pressure, the resulting residue dissolved in EtOAc, and themixture may be washed with saturated aqueous NaCl, dried over Na₂SO₄,filtered, and the filtrate concentrated under reduced pressure to obtainN-(5-bromo-2,4-difluoro-phenyl)thioacetamide, the product of Scheme 2,step B, as a crude oil, suitable for use without additionalpurification.

In Scheme 2, step C, one skilled in the art may recognize thatN-(5-bromo-2,4-difluoro-phenyl)thioacetamide may be cyclized to thebenzothiazole by addition of the appropriate base, such as NaH, Cs₂CO₃,or NaO-t-Bu, in a polar aprotic solvent such as DMF, DMSO, or ACN. Morespecifically, about 1 equivalent of thioamide may be treated with aslight excess of NaO-t-Bu in DMF and heated to about 40° C. withstirring overnight. The product may be isolated utilizing extractiontechniques as are common to one skilled in the art. For example, theconcentrated reaction mixture may be dissolved in EtOAc, washed with H₂Oand saturated aqueous NaCl, dried over MgSO₄, filtered, and concentratedto provide the benzothiazole product of Scheme 2, step C.

In Scheme 2, step D, benzothiazole may undergo carbonylation of the sitebearing the bromine as is well described in the art, using an array ofpalladium catalysts, including PdCl₂, Pd(OAc)₂, or Pd₂(dba)₃, ligandsincluding PPh₃, PBu₃, dppf, or JohnPhos, and carbonyl sources, such asCO, CO/H₂, HCOOLi, HCOOK, in a polar aprotic solvent, such as ACN, DMSO,or DMF. More specifically, about 2 equivalents of HCOOK may be added toa reaction mixture containing about 0.05-0.15 equivalents Pd(OAc)₂,about 0.05-0.15 equivalents of a suitable phosphine ligand, such asJohnPhos, about 1.2 equivalents 1,1,3,3-tetramethylbutyl isocyanide, andabout 1 equivalent 5-bromo-6-fluoro-2-methyl-1,3-benzothiazole dissolvedin a suitable polar solvent, such as DMF. The reaction mixture may beheated to about 65° C., stirred overnight, cooled to RT, and the crudealdehyde product of the palladium-mediated reaction may be isolated andpurified utilizing techniques well known in the art. For example, theresidue may be dissolved in EtOAc, washed sequentially with saturatedaqueous Na₂CO₃ and saturated aqueous NaCl, and purified using silica gelchromatography with a gradient of a mixture of suitable organicsolvents, such as heptane:EtOAc, to obtain the desired carbonylatedbenzothiazole, the product of Scheme 2, step D.

In Scheme 3, step A, 5-bromo-6-fluoro-2-methyl-1,3-benzothiazole iscombined with about 0.03 equivalents of a suitable palladium catalyst,such as [1,3-bis(diphenylphosphino)propane]palladium (II) dichloride ina suitable solvent, such as ethylene glycol, and about 3 equivalents oftrimethylamine under nitrogen. About 5 equivalents of 1-vinyloxybutaneare added to the mixture and the reaction is heated at about 100° C. forabout 18 hours. After cooling to RT, the reaction is treated with excessaqueous HCl and the product,1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanone, is isolated usingstandard extraction techniques well know in the art.

In Scheme 3, step B, 1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanoneis converted to (1S)-1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanolusing a catalytic amount of (R)-Rucy-xylBinap (CAS #1384974-38-2) andabout 0.04 equivalents of potassium tert-butoxide in a suitable solvent,such as toluene, in an autoclave. The autoclave is cooled to about −10°C. and charged to about 450 psi with hydrogen with stirring for about4.5 hours. The reaction is then warmed to RT and stirred for about 15hours, then concentrated, and the product of step B is isolated bytechniques well known in the art, such as flash chromatography.

In Scheme 3, step C,(S)-1-(6-fluoro-2-methylbenzo[d]thiazol-5-yl)ethan-1-ol is dissolved ina suitable solvent, such as dioxane and treated with about 0.5equivalents of 1-formylpyrrolidine and about 2.5 equivalents of benzoylchloride. After stirring for about 36 hours at room temperature, thereaction mixture is cooled to about 0° C., diluted with ethyl acetateand about 1.5 equivalents of N,N-dimethylethylenediamine is addeddropwise to the mixture. The mixture is then warmed to RT, added toexcess saturated aqueous citric acid solution, and the desired product,5-[(1R)-1-chloroethyl]-6-fluoro-2-methyl-1,3-benzothiazole, isolated bystandard extraction techniques followed by purification via flashchromagraphy.

In Scheme 3, step D, the appropriately substituted pyrrolidine isdissolved in a suitable solvent, such as acetonitrile, treated withabout 0.8 equivalents of5-[(1R)-1-chloroethyl]-6-fluoro-2-methyl-1,3-benzothiazole and excesscesium carbonate, and stirred for about 21 hours at about 68° C. Theproduct of Formula I wherein R is methyl is then isolated and purifiedunder conditions well known in the art.

In Scheme 4, steps A through D are carried out in a manner essentiallyanalogous to those described above in Scheme 1, Steps A through D.

In Scheme 5, steps A through D are carried out in a manner essentiallyanalogous to those described above in Scheme 1, Steps A through D.

PREPARATIONS AND EXAMPLES

The following Preparations and Examples further illustrate the inventionand represent typical synthesis of the compound of the invention. Thereagents and starting materials are readily available or may be readilysynthesized by one of ordinary skill in the art. It should be understoodthat the Preparations and Examples are set forth by way of illustrationand not limitation, and that various modifications may be made by one ofordinary skill in the art.

LC-ES/MS is performed on an AGILENT® HP1100 liquid chromatographysystem. Electrospray mass spectrometry measurements (acquired inpositive and/or negative mode) are performed on a Mass SelectiveDetector quadrupole mass spectrometer interfaced to the HP1100 HPLC.LC-MS conditions (low pH): column: PHENOMENEX® GEMINI® NX C18 2.1×50 mm3.0 μm; gradient: 5-100% B in 3 min, then 100% B for 0.75 min columntemperature: 50° C.+/−10° C.; flow rate: 1.2 mL/min; Solvent A:deionized water with 0.1% HCOOH; Solvent B: ACN with 0.1% formic acid;wavelength 214 nm. Alternate LC-MS conditions (high pH): column: XTERRA®MS C18 columns 2.1×50 mm, 3.5 μm; gradient: 5% of solvent A for 0.25min, gradient from 5% to 100% of solvent B in 3 min and 100% of solventB for 0.5 min or 10% to 100% of solvent B in 3 min and at 100% ofsolvent B for 0.75 min; column temperature: 50° C.+/−10° C.; flow rate:1.2 mL/min; Solvent A: 10 mM NH₄HCO₃ pH 9; Solvent B: ACN; wavelength:214 nm.

NMR spectra are performed on a Bruker AVIII HD 400 MHz NMR Spectrometer,obtained as CDCl₃ or DMSO solutions reported in ppm, using residualsolvent [CDCl₃, 7.26 ppm; (CD₃)₂SO, 2.05 ppm] as reference standard.When peak multiplicities are reported, the following abbreviations maybe used: s (singlet), d (doublet), t (triplet), q (quartet), m(multiplet), br-s (broad singlet), dd (doublet of doublets), dt (doubletof triplets). Coupling constants (J), when reported, are reported inhertz (Hz).

Preparation 11-(2-chloro-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidin-6-yl)ethan-1-one

Scheme 1, step A (X═N): To a 0° C. solution of2-chloro-6,7-dihydro-5H-pyrrolo[3,4-d]pyrimidine HCl (10.4 g, 54.2 mmol)in DCM (250 mL) is dropwise added TEA (37 mL, 265 mmol) and acetylchloride (5.2 mL, 73 mmol). The reaction mixture is stirred at RT for 19h. The reaction mixture is diluted with DCM (50 mL) and saturatedaqueous NaHCO₃ solution (200 mL). The aqueous layer is extracted withDCM (2×100 mL). The combined organic extracts are washed with saturatedaqueous NaCl, dried over MgSO₄, filtered, and concentrated under reducedpressure. The resulting residue is dissolved in DCM, adsorbed ontodiatomaceous earth, and purified via flash chromatography over silicagel, eluting with a gradient of 50-100% acetone in hexanes, to obtainthe title compound after solvent evaporation of the desiredchromatographic fractions (5.17 g, 48% yield). ES/MS m/z: 198 (M+H).

Alternative Procedure for Preparation 1

2-Chloro-6,7-dihydro-5H-pyrrolo[3,4-d]pyrimidine hydrochloride (32.0 g,167 mmol; see WO17/071636) is ground to a fine powder with a mortar andpestle. The powder is transferred into a flask and DCM (320 mL) andpyridine (35.0 mL, 433 mmol) are added at RT. The reaction mixture isstirred vigorously in an ice-water bath and acetyl chloride (15.5 mL,217 mmol) is added dropwise over 10 min, maintaining an internaltemperature below 10° C. during the addition. The reaction mixture isstirred vigorously at RT for 2 h, then stirred in an ice-water bath, andaqueous 2M HCl solution (320 mL) is added over 5 min, maintaining aninternal temperature below 15° C. during the addition. The mixture isstirred at RT for 10 min, and is filtered through a short pad ofdiatomaceous earth, washing with DCM (50 mL) and water (50 mL). Thefiltrate is transferred to a separating funnel and the layers areseparated. The aqueous layer is extracted with DCM (3×300 mL), and thecombined organics are dried over Na₂SO₄ and concentrated under reducedpressure. The resulting residue is suspended in 50% cyclopentyl-methylether/heptane (300 mL) and the mixture is stirred vigorously in a 50° C.heating block for 30 minutes. The mixture is stirred at RT for 30 minand is filtered. The filtered solid is dried under vacuum at 40° C.overnight to obtain the title compound (29.38 g, 88% yield) as a palebrown solid. ES/MS m/z: 198 (M+H).

Preparation 2 tert-butyl(2S,4R)-4-((6-acetyl-6,7-dihydro-5H-pyrrolo[3,4-d]pyrimidin-2-yl)oxy)-2-methylpyrrolidine-1-carboxylate

Scheme 1, step B (X═N): To a solution of tert-butyl(2S,4R)-4-hydroxy-2-methyl-pyrrolidine-1-carboxylate (2.07 g, 10.3 mmol)and THF (20 mL) at 0° C. is added 60% mass NaH in mineral oil (0.83 g,20.7 mmol) in one portion and the mixture stirred for 25 min.1-(2-chloro-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidin-6-yl)ethan-1-one (2.5g, 12.7 mmol) and additional THF (5 mL) is added, the mixture is allowedto warm slowly to RT over 45 min, and the mixture is stirred at RT for19 h. The reaction mixture is diluted with water (75 mL) and EtOAc (75mL). The aqueous layer is extracted with EtOAc (2×50 mL), and thecombined organic extracts are dried over MgSO₄, filtered, andconcentrated under reduced pressure. The resulting residue is dissolvedin DCM and purified via flash chromatography over silica gel, elutingwith a gradient of 50-90% acetone in hexanes, to obtain the titlecompound after solvent evaporation of the desired chromatographicfractions (3.07 g, 82% yield). ES/MS m/z: 307 (M+H—C₄H₉).

Alternative Procedure for Preparation 2

To a flask is added 60% NaH in mineral oil (5.37 g, 134 mmol) and THF(54 mL) at RT. The flask is stirred in an ice-water bath and a solutionof tert-butyl (2S,4R)-4-hydroxy-2-methyl-pyrrolidine-1-carboxylate (13.5g, 67.1 mmol, see J. Med. Chem. 1988, 31, 1598-1611) in THF (54 mL) isadded over 5 min, maintaining an internal temperature below 10° C.during the addition. The reaction mixture is stirred at RT forapproximately 15 min and subsequently in a 41° C. heating block forapproximately 10 min. To the mixture is added a slurry of1-(2-chloro-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidin-6-yl)ethan-1-one(20.1 g, 101 mmol) in THF (297 mL) dropwise with a peristaltic pump over1 h. The reaction mixture is stirred in a 40° C. heating blockovernight, cooled to 0° C. in an ice-water bath, and saturated aqueousNH₄Cl solution (120 mL) is added over 5 min. 2-Methyltetrahydrofuran (10mL) is added. The mixture is stirred at RT for 5 min, is transferred toa separating funnel, and the layers are separated. The aqueous layer isextracted with 2-methyltetrahydrofuran (130 mL) and the combined organicextracts are dried over Na₂SO₄, filtered, and the filtrate isconcentrated under reduced pressure to give the title compound (35.2g, >99% yield) as a dark red/brown oil. ES/MS m/z: 385 (M+Na).

Preparation 31-(2-(((3R,5S)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidin-6-yl)ethan-1-onehydrochloride

Scheme 1, step C (X═N): To a solution of tert-butyl(2S,4R)-4-((6-acetyl-6,7-dihydro-5H-pyrrolo[3,4-d]pyrimidin-2-yl)oxy)-2-methylpyrrolidine-1-carboxylate(1.8 g, 5 mmol) in DCM (25 mL) is added a 4M solution of HCl in1,4-dioxane (6.2 mL, 25 mmol). The resulting mixture is stirred at RTfor 4 h. The resulting suspension is concentrated under reduced pressureand the resulting residue is placed under vacuum for 1 h to obtain thetitle compound (1.48 g, >99% yield). ES/MS m/z: 263 (M+H).

Preparation 41-(2-(((3R,5S)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidin-6-yl)ethan-1-one

To a flask is added tert-butyl(2S,4R)-4-[(6-acetyl-5,7-dihydropyrrolo[3,4-d]pyrimidin-2-yl)oxy]-2-methyl-pyrrolidine-1-carboxylate(35.23 g, 67.1 mmol) and isopropyl acetate (176 mL). The reactionmixture is stirred in an ice-water bath (internal temperature 10° C.)and an aqueous 5M solution of HCl (176 mL, 880 mmol) is added dropwiseover 5 min, maintaining an internal temperature below 15° C. during theaddition. The reaction mixture is stirred at RT for 1 h, the mixture istransferred to a separating funnel with ethyl acetate (5 mL) and water(5 mL), and the layers are separated. The aqueous layer is cooled in anice-water bath and DCM (180 mL) and water (180 mL) are added. Themixture is stirred vigorously and solid potassium phosphate monohydrate(185 g, 803.37 mmol) is added over 5 min. The mixture is stirred at RTfor 5 min, passed through a short pad of diatomaceous earth, washingwith DCM (50 mL) and water (50 mL), and the layers are separated. To theaqueous layer is added solid potassium phosphate monohydrate (23.2 g,101 mmol), the mixture is stirred at RT for 5 min, and the mixture isextracted with DCM (3×180 mL). The combined organics are dried overNa₂SO₄ and concentrated under reduced pressure to give the titlecompound (18.23 g, 67% yield) as a brown foamy solid. ES/MS m/z: 263(M+H).

Preparation 51-(2-chloro-5,7-dihydro-6H-pyrrolo[3,4-b]pyridin-6-yl)ethan-1-one

Scheme 1, step A (X═CH): To a 0° C. solution of2-chloro-6,7-dihydro-5H-pyrrolo[3,4-b]pyridine hydrochloride (1.0 g, 5.2mmol) in DCM (13 mL) is dropwise added DIPEA (3.6 mL, 21 mmol) andacetyl chloride (0.4 mL, 6 mmol). The reaction mixture is stirred at RTfor 24 h. The resulting mixture is diluted with DCM (20 mL) andsaturated aqueous NaHCO₃ (30 mL). The aqueous layer is extracted withDCM (2×30 mL). The combined organic extracts are dried over MgSO₄,filtered, and concentrated under reduced pressure. The resulting residueis dissolved in DCM, adsorbed onto diatomaceous earth, and purified viaflash chromatography over silica gel, eluting with a gradient of 50-100%acetone in hexanes, to obtain the title compound after solventevaporation of the desired chromatographic fractions (0.95 g, 92%yield). ES/MS m/z: 197 (M+H).

Preparation 6 tert-butyl(2S,4R)-4-((6-acetyl-6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-2-yl)oxy)-2-methylpyrrolidine-1-carboxylate

Scheme 1, step B (X═CH): To a solution of tert-butyl(2S,4R)-4-hydroxy-2-methyl-pyrrolidine-1-carboxylate (0.41 g, 2.03mmol), 1-(2-chloro-5,7-dihydro-6H-pyrrolo[3,4-b]pyridin-6-yl)ethan-1-one(0.47 g, 2.36 mmol), and THF (8 mL) at RT is portion wise added KO-t-Bu(0.45 g, 4 mmol) and the mixture is stirred at 50° C. for 4.5 h. Thereaction mixture is diluted with water (50 mL) and EtOAc (50 mL). Theaqueous layer is extracted with EtOAc (2×50 mL), and the combinedorganic extracts are dried over MgSO₄, filtered, and concentrated underreduced pressure. The resulting residue is dissolved in DCM and purifiedvia flash chromatography over silica gel, eluting with a gradient of40-100% acetone in hexanes, to obtain the title compound after solventevaporation of the desired chromatographic fractions (0.34 g, 47%yield). ES/MS m/z: 262 (M+H—C₄H₉).

Preparation 71-(2-(((3R,5S)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-b]pyridin-6-yl)ethan-1-onehydrochloride

Scheme 1, step C (X═CH): To a solution of tert-butyl(2S,4R)-4-((6-acetyl-6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-2-yl)oxy)-2-methylpyrrolidine-1-carboxylate(0.34 g, 0.94 mmol) in DCM (5.0 mL) is added a 4M solution of HCl in1,4-dioxane (1.2 mL, 4.8 mmol). The resulting mixture is stirred at RTfor 3 h. The resulting suspension is concentrated under reducedpressure, and the resulting residue is placed under vacuum for 1 h toobtain the title compound (0.28 g, >99% yield). ES/MS m/z: 262 (M+H).

Preparation 8 N-(5-bromo-2,4-difluoro-phenyl)acetamide

Scheme 2, step A: To a flask is added Ac₂O (389 mL) with stirring in aheating block at about 61° C. (internal temperature 60° C.). To theflask is added 5-bromo-2,4-difluoroaniline (77.7 g, 374 mmol) portionwise over 30 min, maintaining an internal temperature below 65° C.during the addition. The reaction mixture is stirred in a heating blockat about 61° C. for 10 min, and cooled to RT to give a residue which isconcentrated from toluene (4×200 mL) to give a pale brown/pink solid.The concentrated solid is suspended in heptane (80 mL) and the mixtureis agitated on a rotary evaporator in a 50° C. water bath for 15 min atatmospheric pressure, cooled to RT, and filtered. The filtered solid iscollected and dried under vacuum at 40° C. for 2 h to obtain the titlecompound (89.6 g, 95% yield) as an off-white solid. ES/MS m/z: 250(M+H).

Preparation 9 N-(5-bromo-2,4-difluoro-phenyl)thioacetamide

Scheme 2, step B: To a solution ofN-(5-bromo-2,4-difluoro-phenyl)acetamide (89.6 g, 358 mmol) in anhydrousACN (896 mL) is addedpyridin-1-ium-1-yl-[pyridin-1-ium-1-yl(sulfido)phosphinothioyl]sulfanyl-sulfido-thioxo-phosphane(68.2 g, 179 mmol, J. Org. Chem. 2011, 76, 1546-1553) at RT. The slurryis stirred in a 85° C. heating block overnight (internal temperature 80°C.), cooled to RT, and poured into a mixture of ice (200 g) andsaturated aqueous NaCl (700 mL). The mixture is diluted with EtOAc (900mL) stirred at RT for 10 min, the layers are separated, and the aqueouslayer additionally extracted with EtOAc (900 mL). The combined organicextracts are washed with saturated aqueous NaCl solution (900 mL), driedover Na₂SO₄, and concentrated under reduced pressure to give the titlecompound as a dark brown oil, which is dissolved in DMF (953 mL) at RT,and used without additional purification.

Preparation 10 5-bromo-6-fluoro-2-methyl-1,3-benzothiazole

Scheme 2, step C: To a DMF solution ofN-(5-bromo-2,4-difluoro-phenyl)thioacetamide is added NaO-t-Bu (42.6 g,430 mmol) portion wise over 20 min with stirring, maintaining aninternal temperature below 30° C. The reaction mixture is stirred at RTfor 5 min, stirred overnight in a 42° C. heating block (internaltemperature 40° C.), and cooled to RT. The reaction mixture is addeddropwise to a mixture of ice (250 g) and H₂O (700 mL) over 5 min,maintaining an internal temperature below 20° C. The mixture is stirredat RT for 10 min and filtered. The filtered solid is dried under vacuumat 40° C. overnight, and suspended in 50% MeOH/H₂O (480 mL). The mixtureis stirred in a 45° C. heating block for 15 min, cooled to RT, andfiltered. The filtered solid is dried under vacuum at 40° C. for 72 h togive a pale brown solid. The material is combined with EtOAc (700 mL)and the mixture is stirred at RT for 10 min, H₂O (700 mL) is added, andthe layers separated. The aqueous layer is extracted with EtOAc (700mL), then the combined organic extracts are washed with saturatedaqueous NaCl (700 mL), dried over MgSO₄, and concentrated under reducedpressure to give the title compound (62.7 g, 71% yield) as a brownsolid. ¹H NMR (d₆-DMSO) δ: 2.82 (s, 3H), 7.57 (m, 1H), 8.12 (m, 1H).

Preparation 11 6-fluoro-2-methyl-1,3-benzothiazole-5-carbaldehyde

Scheme 2, step D: 5-bromo-6-fluoro-2-methyl-1,3-benzothiazole (100.9 g,410 mmol) in DMF (1009 mL) is sparged with N₂ for 5 min at RT withstirring. Potassium formate (52.3 g, 615.0 mmol), palladium(II) acetate(2.82 g, 12.30 mmol), 2-(di-tert-butylphosphino)biphenyl (5.19 g, 17.2mmol) and 1,1,3,3-tetramethylbutyl isocyanide (90.8 mL, 492.0 mmol) areadded and the mixture is sparged with N₂ for 30 min at RT with stirring.The reaction mixture is stirred overnight at an internal temperature of65° C., cooled to 20-25° C., and 2M aqueous HCl solution (820 mL) isadded dropwise over 30 min, maintaining an internal temperature below30° C. The resulting mixture is stirred at 20-25° C. for 2 h and dilutedwith EtOAc (1.5 L) and H₂O (1 L). The layers are separated and theorganic layer is washed with 10% aqueous N-acetyl-cysteine solution (2×1L), saturated aqueous Na₂CO₃ (750 mL×2) and saturated aqueous NaCl (750mL); the organic extract is dried over MgSO₄ and concentrated underreduced pressure to provide the first batch of crude material. Theaqueous HCl layer from the first extraction is further extracted withEtOAc (1 L, then 500 mL), and the combined organic extracts are washedwith saturated aqueous NaCl (500 mL), dried over MgSO₄, and concentratedunder reduced pressure to provide the second batch of crude material.The combined aqueous N-acetyl-cysteine layers are then extracted withEtOAc (1 L, then 500 mL) and the combined organic extracts are washedsequentially with saturated aqueous Na₂CO₃ (500 mL) and saturatedaqueous NaCl (500 mL); the combined organic extracts are dried overMgSO₄ and concentrated under reduced pressure to provide the third batchof crude material. The three batches of crude material are combined inMTBE (250 mL) and heptane (250 mL) and the resulting slurry is stirredat RT for 20 min. The resulting precipitate is filtered and washed withheptane (250 mL). The filtered solid is dried under vacuum at 45° C. togive a first batch of product. The filtrate is concentrated and theresidue is purified by column chromatography over silica, eluting with agradient of 0-100% EtOAc/heptane. The product-containing fractions arecombined and concentrated to a volume of approximately 400 mL, theresulting slurry is stirred at RT for 15 min, filtered, and the filteredsolid is washed with heptane (200 mL), to give a second batch ofproduct. The first and second batches of product are combined withheptane (500 mL), slurried at RT, filtered, and the filtered solid iswashed with heptane (250 mL). The filtered solid is dried under vacuumat 45° C. overnight to give the title compound (63.5 g, 79% yield).ES/MS m/z: 196 (M+H).

Preparation 121-(6-chloro-1,3-dihydropyrrolo[3,4-c]pyridin-2-yl)ethanone

Scheme 4, step A: To a scintillation vial is added6-chloro-2,3-dihydro-1H-pyrrolo[3,4-c]pyridine;hydrochloride (1.6 g, 8.4mmol), dichloromethane (21 mL) and N,N-diisopropylethylamine (6 mL, 34mmol). The mixture is capped, cooled to 0° C. in an ice bath and acetylchloride (0.7 mL, 10 mmol) is added dropwise. The reaction mixture isremoved from ice bath and is stirred at room temperature for 24 h.Saturated aqueous sodium bicarbonate solution (20 mL) and water (5 mL)is added and stirred 5 minutes. The organic layer is removed. Theaqueous layer is extracted with dichloromethane (2×10 mL). The combinedorganic phases are dried over magnesium sulfate, filtered, andconcentrated under reduced pressure. The residue is dissolved indichloromethane, loaded on silica cartridge and purified via flashchromatography eluting with hexanes:acetone [60:40 to 0:100] to give thetitle compound1-(6-chloro-1,3-dihydropyrrolo[3,4-c]pyridin-2-yl)ethanone (1.51 g, 7.7mmol, 91% yield). ES/MS m/z: 197 (M+H).

Preparation 13 Tert-butyl(2S,4R)-4-[(2-acetyl-1,3-dihydropyrrolo[3,4-c]pyridin-6-yl)oxy]-2-methyl-pyrrolidine-1-carboxylate

Scheme 4, step B: To a scintillation vial is added tert-butyl(2S,4R)-4-hydroxy-2-methyl-pyrrolidine-1-carboxylate (0.3 g, 1.49 mmol),1-(6-chloro-1,3-dihydropyrrolo[3,4-c]pyridin-2-yl)ethanone (0.35 g, 1.78mmol) and tetrahydrofuran (6 mL). Mixture is stirred at RT to give awhite suspension. Potassium tert-butoxide (0.35 g, 3.09 mmol) is addedportion wise. The mixture is capped and is heated at 45° C. for 5 hours.The mixture poured into a separatory funnel containing water (30 mL) andethyl acetate (30 mL). The organic layer is separated and aqueous phaseextracted with ethyl acetate (2×30 mL). The combined organic phase isdried over magnesium sulfate, filtered, and concentrated under reducedpressure. The residue is purified via flash chromatography to give thetitle compound tert-butyl(2S,4R)-4-[(2-acetyl-1,3-dihydropyrrolo[3,4-c]pyridin-6-yl)oxy]-2-methyl-pyrrolidine-1-carboxylate(0.121 g, 0.334 mmol, 22% yield). ES/MS m/z: 306 (M+H—C₄H₉).

Preparation 141-[6-[(3R,5S)-5-methylpyrrolidin-3-yl]oxy-1,3-dihydropyrrolo[3,4-c]pyridin-2-yl]ethanone;hydrochloride

Scheme 4, step C: To a solution of tert-butyl(2S,4R)-4-[(2-acetyl-1,3-dihydropyrrolo[3,4-c]pyridin-6-yl)oxy]-2-methyl-pyrrolidine-1-carboxylate(0.120 g, 0.332 mmol) in dichloromethane (3 mL) is added hydrochloricacid in 1,4-dioxane (0.4 mL, 2 mmol, 4 M solution). The mixture isstirred at room temperature for 3 h. The suspension is concentratedunder reduced pressure and the residue is placed under vacuum for 1 h togive1-[6-[(3R,5S)-5-methylpyrrolidin-3-yl]oxy-1,3-dihydropyrrolo[3,4-c]pyridin-2-yl]ethanone;hydrochloride(0.099 g, 0.299 mmol, 100% yield). MS m/z: 262 (M+H).

Preparation 15 1-(3-bromo-5,7-dihydropyrrolo[3,4-b]pyridin-6-yl)ethanone

Scheme 5, step A: To a 0° C. solution of3-bromo-6,7-dihydro-5H-pyrrolo[3,4-b]pyridine;hydrochloride (0.52 g, 2.2mmol) in dichloromethane (6 mL) is dropwise addedN,N-diisopropylethylamine (1.5 mL, 8.6 mmol) and acetyl chloride (0.2mL, 3 mmol). The reaction mixture is stirred at room temperature for 24h. Added saturated aqueous sodium bicarbonate solution (15 mL) andstirred 5 min and removed the organic layer. The aqueous layer isextracted with dichloromethane (2×25 mL). The combined organic phase isdried over magnesium sulfate, filtered, and concentrated under reducedpressure. The residue is dissolved in dichloromethane, adsorbed ontocelite, and purified via flash chromatography (silica gel) eluting withhexanes:acetone [50:50 to 0:100] to give1-(3-bromo-5,7-dihydropyrrolo[3,4-b]pyridin-6-yl)ethanone (0.440 g, 1.8mmol, 83% yield). ES/MS m/z: 241 and 243 (M and M+2).

Preparation 16 tert-butyl(2S,4R)-4-[(6-acetyl-5,7-dihydropyrrolo[3,4-b]pyridin-3-yl)oxy]-2-methyl-pyrrolidine-1-carboxylate

Scheme 5, step B: To a scintillation vial with tert-butyl(2S,4R)-4-hydroxy-2-methyl-pyrrolidine-1-carboxylate (0.399 g, 1.98mmol), 1-(3-bromo-5,7-dihydropyrrolo[3,4-b]pyridin-6-yl)ethanone (0.300g, 1.24 mmol), cesium carbonate (1.22 g, 3.74 mmol) andmethanesulfonato(2-di-t-butylphosphino-3,4,5,6-tetramethyl-2′,4′,6′-tri-i-propylbiphenyl)(2′-amino-1,1′-biphenyl-2-yl)palladium(II)(0.28 g, 0.33 mmol) is added toluene (12 mL) and the mixture is cappedand is heated at 75° C. for 72 hours. The reaction mixture is cooled andfiltered through celite using acetone to rinse. The filtrate isconcentrated under reduced pressure. The residue is taken up indichloromethane and purified via flash chromatography (silica gel)eluting with hexane:acetone [1:1 to 0:1] to give tert-butyl(2S,4R)-4-[(6-acetyl-5,7-dihydropyrrolo[3,4-b]pyridin-3-yl)oxy]-2-methyl-pyrrolidine-1-carboxylate(0.109 g, 0.301 mmol, 24% yield). ES/MS m/z: 306 (M+H—C₄H₉).

Preparation 171-[3-[(3R,5S)-5-methylpyrrolidin-3-yl]oxy-5,7-dihydropyrrolo[3,4-b]pyridin-6-yl]ethanone;hydrochloride

Scheme 5, step C: To a solution of tert-butyl(2S,4R)-4-[(6-acetyl-5,7-dihydropyrrolo[3,4-b]pyridin-3-yl)oxy]-2-methyl-pyrrolidine-1-carboxylate(0.108 g, 0.299 mmol) in dichloromethane (3 mL) is added hydrochloricacid in 1,4-dioxane (0.4 mL, 2 mmol, 4 M solution). The mixture isstirred at room temperature for 2.5 h. The suspension is concentratedunder reduced pressure and the residue is placed under vacuum for 1 h togive1-[3-[(3R,5S)-5-methylpyrrolidin-3-yl]oxy-5,7-dihydropyrrolo[3,4-b]pyridin-6-yl]ethanone;hydrochloride(0.089 g, 0.299 mmol, 100% yield). MS m/z: 262 (M+H).

Preparation 18 1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanone

Scheme 3, step A: Purge a flask containing5-bromo-6-fluoro-2-methyl-1,3-benzothiazole (30.6 g, 124 mmol) and[1,3-bis(diphenylphosphino)propane]palladium (II) dichloride (2.32 g,3.85 mmole) with nitrogen and add ethylene glycol (240 mL) andtrimethylamine (50 mL, 359 mmol) and 1-vinyloxybutane (80 mL, 618 mmol).Heat the reaction at 100° C. for 18 h. Cool the reaction to roomtemperature and add 2.5 M aqueous HCl (500 mL, 1.300 mol) and stir for 1hour. And ethyl acetate (400 mL) and remove the organic layer. Extractthe aqueous layer with EtOAc (2×225 mL). Dry the combined organic layerover magnesium sulfate, filter, and concentrate. Suspend the crudeproduct in 65:35 water:MeOH, filter the slurry, and dry the solid toafford the title compound1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanone (16.7 g, 79.8 mmol,64% yield). ES/MS m/z: 210 (M+H).

Alternative Preparation of1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanone

To a flask is added 5-bromo-6-fluoro-2-methyl-1,3-benzothiazole (72.0 g,293 mmol), 1,3-bis(diphenylphosphino)propane (2.41 g, 5.85 mmol) andpalladium(II) acetate (0.657 g, 2.93 mmol) at room temperature under N₂.To the flask is added ethylene glycol (720 mL), 1-vinyloxybutane (189mL, 1460 mmol) and triethylamine (124 mL, 878 mmol). N₂ is bubbledthrough the reaction mixture for 30 minutes with stirring at roomtemperature, then the reaction mixture is stirred overnight in a 115° C.heating block with a condenser fitted (internal temperature 98° C.). Thereaction mixture is cooled to room temperature and is poured into amixture of aq. 2M HCl (576 mL) and ice (50 g) over 15 minutes withice-water bath cooling, maintaining an internal temperature below 20° C.during the addition. The mixture is stirred at room temperature for 5minutes, then is stirred in a 41° C. heating block for 30 minutes(internal temperature 40° C.). The reaction mixture is diluted withEtOAc (500 mL) and the mixture is stirred at room temperature for 10minutes, then is filtered through diatomaceous earth. The filtrate istransferred to a separating funnel and the layers are separated. Theaqueous layer is extracted with EtOAc (500 mL), then the combinedorganics are washed with sat. aq. NaCl solution (500 mL), dried overNa₂SO₄ and concentrated. The resultant residue is suspended in 35%MeOH/water (162 mL) and the mixture is vigorously agitated in a 45° C.water bath on a rotary evaporator for 30 minutes, then is cooled to roomtemperature and filtered. The filtered solid is dried under vacuum at40° C. overnight to give the title compound (57.48 g, 93% yield) as abrown solid. ES/MS m/z: 210 (M+H)

Preparation 19 (1S)-1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanol

Scheme 3, step B: To an autoclave is added1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanone (16.7 g, 79.8 mmol)and (R)-Rucy-xylBinap (CAS #1384974-38-2) (0.465 g, 0.385 mmol) and a 1Msolution of potassium tert-butoxide in tert-butanol (3.5 mL, 3.5 mmol)and toluene (240 mL). The autoclave is cooled to −10° C. and charged to450 psi with hydrogen with stirring at 500 rpm for 4.5 hours. Thereaction is warmed to room temperature and stirred for 15 hours. Thereaction mixture is concentrated. The residue is purified via flashchromatography (silica gel) eluting with a gradient of 0-40% EtOAc inhexanes to give (1S)-1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanol(15.8 g, 74.8 mmol, 94% yield). ES/MS m/z: 212 (M+H). [α]_(D) ²⁰=−38.6°(c=0.2, MeOH).

Alternative Preparation of(1S)-1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanol

To a flask is added 1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethanone(50.1 g, 239 mmol), 2-propanol (311 mL), aq. pH 7 potassium phosphatebuffer solution (0.1 M, 752 mL), KRED-P3-C12 (5.51 g; CodexisKetoreductase (KRED), lyophyilized enzyme powder, carbonyl reductase,CAS #77106-95-7), magnesium sulfate (0.173 g, 1.44 mmol) and NADP (0.501g) at room temperature. The mixture is stirred in a 37° C. heating block(internal temperature 36° C.) open to air overnight, then to the mixtureis added KRED-P3-C12 (2.51 g), magnesium sulfate (0.0865 g, 0.718 mmol)and NADP (0.251 g) and the reaction mixture is stirred in a 37° C.heating block (internal temperature 36° C.) overnight open to air undera stream of N₂ gas. To the reaction mixture is added 2-propanol (146mL), KRED-P3-C12 (2.51 g), magnesium sulfate (0.0865 g, 0.718 mmol) andNADP (0.251 g) and the reaction mixture is stirred in a 37° C. heatingblock (internal temperature 36° C.) overnight open to air under a streamof N₂ gas. To the reaction mixture is added 2-propanol (91.5 mL),KRED-P3-C12 (0.501 g), magnesium sulfate (0.0288 g, 0.239 mmol) and NADP(0.0501 g) and the reaction mixture is stirred in a 37° C. heating block(internal temperature 36° C.) overnight open to air under a stream of N₂gas. The reaction mixture is diluted with water (400 mL) and EtOAc (400mL) and filtered through diatomaceous earth, washing with water (100 mL)and EtOAc (100 mL). The filtrate is transferred to a separating funneland the layers are separated. The aqueous layer is extracted with EtOAc(500 mL), then the combined organics are washed with water (1 L), driedover Na₂SO₄ and concentrated to give the title compound (48.7 g, 96%yield) as a brown solid. Optical rotation [α]_(D) ²⁰=−35° (c=0.2, MeOH).ES/MS m/z: 212 (M+H).

Preparation 205-[(1R)-1-chloroethyl]-6-fluoro-2-methyl-1,3-benzothiazole

Scheme 3, step C: To a solution of(S)-1-(6-fluoro-2-methylbenzo[d]thiazol-5-yl)ethan-1-ol (15.8 g, 74.8mmol) in dioxane (400 mL) is added 1-formylpyrrolidine (3.7 mL, 38 mmol)and benzoyl chloride (22 mL, 187 mmol). The reaction is stirred at roomtemperature for 36 h. The reaction is cooled to 0° C. and ethyl acetate(250 mL) is added followed by dropwise addition ofN,N-dimethylethylenediamine (12 mL, 110 mmol). The solution is warmed toroom temperature and stirred for 10 minutes. To the solution is addedsaturated aqueous citric acid solution (200 mL). The solution is dilutedwith ethyl acetate (250 mL) and water (250 mL). The aqueous layer isremoved and extracted with ethyl acetate (2×125 mL). The combine organiclayers are washed with saturated aqueous sodium carbonate (200 mL). Thisaqueous wash is back extracted with ethyl acetate (100 mL). The combinedorganic layers are washed with brine (100 mL) and then dried overmagnesium sulfate, filtered, and concentrated. The residue is purifiedby via flash chromatography (silica gel) eluting with hexanes:DCM (97:3to 50:50) to give5-[(1R)-1-chloroethyl]-6-fluoro-2-methyl-1,3-benzothiazole (13.2 g, 57.6mmol, 77% yield). ES/MS m/z: 230 (M+H).

Example 11-(2-(((3R,5S)-1-((6-fluoro-2-methylbenzo[d]thiazol-5-yl)methyl)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidin-6-yl)ethan-1-one

Scheme 1, step D (X═N): To a solution of6-fluoro-2-methyl-1,3-benzothiazole-5-carbaldehyde (0.920 g, 4.71 mmol)and1-(2-(((3R,5S)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidin-6-yl)ethan-1-onehydrochloride (1.48 g, 4.95 mmol) in DCM (46 mL) is added DIPEA (2.4 mL,14 mmol). The resulting solution is stirred at RT for 1 h. To thesolution is added NaBH(OAc)₃ (3.0 g, 14.2 mmol). The resulting solutionis stirred at RT for 16 h. The reaction mixture is quenched slowly withsaturated aqueous NaHCO₃ (10 mL) and diluted with water (50 mL). Theaqueous layer is extracted with DCM (2×50 mL). The combined organicextracts are dried over MgSO₄, filtered, and concentrated under reducedpressure. The resulting residue is dissolved in DCM and purified viaflash chromatography over silica gel, eluting with a gradient of 10-100%acetone in hexanes followed by isocratic 10% methanol in EtOAc to obtainthe title compound after solvent evaporation of the desiredchromatographic fractions (1.68 g, 81% yield). ES/MS m/z: 442 (M+H);[α]_(D) ²⁰=+55.3° (c=0.2, MeOH).

Alternative Procedure for Example 1

To a flask is added1-(2-(((3R,5S)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidin-6-yl)ethan-1-one(18.2 g, 45.1 mmol) and DCM (178 mL). The mixture is stirred in anice-water bath (internal temperature 5° C.) and to the mixture is added6-fluoro-2-methyl-1,3-benzothiazole-5-carbaldehyde (8.9 g, 45.1 mmol),pyridine (7.3 mL, 90 mmol) and NaBH(OAc)₃ (19.1 g, 90.1 mmol). Thereaction mixture is stirred at RT overnight (internal temperature 20°C.), cooled in an ice-water bath, and aqueous 10% Na₂CO₃ solution (130mL) is added over 5 min, maintaining an internal temperature below 15°C. during the addition. The mixture is stirred vigorously at RT for 15min, the layers are separated, and the aqueous layer is extracted withDCM (2×90 mL). The combined organic extracts are dried over Na₂SO₄,filtered, and the filtrate is concentrated to give a residue, which ispurified by flash chromatography over silica, using a gradient of 0-15%isopropanol/DCM. The product-containing fractions are concentrated underreduced pressure. The resulting residue is concentrated from heptane(100 mL) to obtain the title compound (15.64 g, 76% yield) as acream-colored solid. The solid is combined with two other lots ofsimilar purity and the combined material (19.86 g, 43.65 mmol) iscombined with EtOAc (149 mL) and heptane (149 mL) at RT. The mixture isstirred vigorously in a 45° C. heating block for 30 min, cooled to RTand stirred for 15 min, and is filtered. The filtered solid is driedunder vacuum at 40° C. overnight to give the title compound (18.81 g,96% yield) as an off-white solid. ES/MS m/z: 442 (M+H); [α]_(D)²⁰=+59.8° (c=0.2, MeOH).

Example 21-(2-(((3R,5S)-1-((6-fluoro-2-methylbenzo[d]thiazol-5-yl)methyl)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-b]pyridin-6-yl)ethan-1-one

Scheme 1, step D (X═CH): To a solution of6-fluoro-2-methyl-1,3-benzothiazole-5-carbaldehyde (0.19 g, 0.95 mmol)and1-(2-(((3R,5S)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-b]pyridin-6-yl)ethan-1-onehydrochloride (0.28 g, 0.94 mmol) in DCM (9 mL) is added DIPEA (0.45 mL,2.6 mmol). The resulting solution is stirred at RT for 40 min. To thesolution is added NaBH(OAc)₃ (0.65 g, 3.04 mmol). The resulting solutionis stirred at RT for 17 h. The reaction mixture is quenched slowly withsaturated aqueous NaHCO₃ (5 mL). The aqueous layer is extracted with DCM(2×5 mL). The combined organic extracts are dried over MgSO₄, filtered,and concentrated under reduced pressure. The resulting residue isdissolved in DCM and purified via flash chromatography over silica gel,eluting with a gradient of 40-100% acetone in hexanes, to obtain thetitle compound after solvent evaporation of the desired chromatographicfractions (0.27 g, 65% yield). ES/MS m/z: 441 (M+H); [α]_(D) ²⁰=+101.4°(c=0.2, MeOH).

Alternative Preparation of1-(2-(((3R,5S)-1-((6-fluoro-2-methylbenzo[d]thiazol-5-yl)methyl)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-b]pyridin-6-yl)ethan-1-onePreparation of 4-Methylbenzenesulfonicacid;(3R,5S)-5-methylpyrrolidin-3-ol

To a flask is added tert-butyl(2S,4R)-4-hydroxy-2-methyl-pyrrolidine-1-carboxylate (53.0 g, 263 mmol)and 2-propanol (265 mL) at room temperature. The mixture is stirred atroom temperature (internal temperature 20° C.) and p-toluenesulfonicacid monohydrate (60.1 g, 316 mmol) is added in one portion. Thereaction mixture is stirred in a 62° C. heating block overnight, then iscooled to room temperature and concentrated to approximately 150 mLtotal volume. The mixture is diluted with MTBE (530 mL) and the mixtureis stirred vigorously at room temperature for 30 minutes and then isfiltered under flow of N₂ gas. The filtered solid is dried under vacuumat 40° C. for 2 hours to provide 4-methylbenzenesulfonicacid;(3R,5S)-5-methylpyrrolidin-3-ol (67.6 g, 93% yield) as a whitesolid. ES/MS m/z: 102 (M+H).

Preparation of(3R,5S)-1-[(6-Fluoro-2-methyl-1,3-benzothiazol-5-yl)methyl]-5-methyl-pyrrolidin-3-ol

To a flask is added 4-methylbenzenesulfonicacid;(3R,5S)-5-methylpyrrolidin-3-ol (61.9 g, 226 mmol), EtOAc (850 mL)and 6-fluoro-2-methyl-1,3-benzothiazole-5-carbaldehyde (42.5 g, 216mmol) at room temperature. The reaction mixture is stirred in anice-water bath (internal temperature 3° C.) and triethylamine (60.1 mL,431 mmol) is added in one portion. The reaction mixture is stirred in anice-water bath for 30 minutes, then sodium triacetoxyborohydride (91.4g, 431 mmol) is added in one portion. The reaction mixture is stirred inan ice-water bath for 10 minutes, then at room temperature for 2 hours(internal temperature 20° C.). The reaction mixture is stirred in anice-water bath and 15% aq. KHSO₄ solution (650 mL) is added over 5minutes, maintaining an internal temperature below 15° C. during theaddition. The mixture is stirred vigorously at room temperature for 1hour, then sat. aq. citric acid solution (100 mL) is added and themixture is stirred at room temperature for 5 minutes, then the layersare separated. The aqueous layer is washed with EtOAc (400 mL), then theaqueous layer is stirred in an ice-water bath and solid Na₂CO₃ (80 g) isadded portionwise over 10 minutes with vigorous stirring until pH=10(measured by pH paper). The aqueous layer is then extracted with EtOAc(3×400 mL). The combined organics are dried over Na₂SO₄ and concentratedto give a residue that is crushed into a fine powder using a pestle andmortar, then is combined with 25% MTBE/heptane (280 mL). The mixture isstirred vigorously in a 45° C. heating block for 1 hour, then at roomtemperature for 1 hour and then is filtered to give the first batch offiltered solid. The filtrate is concentrated, then the residue iscombined with 25% MTBE/heptane (40 mL) and the mixture is stirredvigorously at room temperature for 30 minutes and then is filtered togive the second batch of filtered solid. The first and second batches offiltered solids are combined and the mixture is ground up with aspatula, then is dried under vacuum at room temperature overnight toprovide(3R,5S)-1-[(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)methyl]-5-methyl-pyrrolidin-3-ol(53.3 g, 87% yield) as a cream-coloured solid. ES/MS m/z: 281 (M+H).

Preparation of final title compound1-(2-(((3R,5S)-1-((6-fluoro-2-methylbenzo[d]thiazol-5-yl)methyl)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-b]pyridin-6-yl)ethan-1-one

To a flask is added(3R,5S)-1-[(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)methyl]-5-methyl-pyrrolidin-3-ol(26.9 g, 95.0 mmol),1-(2-chloro-5,7-dihydropyrrolo[3,4-b]pyridin-6-yl)ethanone (22.1 g, 109mmol), cesium carbonate (92.8 g, 285 mmol), MorDalPhos (1.76 g, 3.80mmol), palladium(II)(pi-cinnamyl) chloride dimer (984 mg, 1.90 mmol) andtoluene (538 mL) at room temperature. N₂ gas is bubbled through themixture at room temperature with stirring for 30 minutes, then thereaction mixture is stirred in a 86° C. heating block overnight(internal temperature 80° C.). The reaction mixture is cooled to roomtemperature and diluted with EtOAc (269 mL) and diatomaceous earth (27g) is added. The mixture is stirred at room temperature for 5 minutes,then is filtered through diatomaceous earth, washing with EtOAc (200mL). The filtrate is concentrated to give a residue, which is dissolvedin EtOAc (100 mL) and the mixture is passed through a short pad ofsilica gel (300 g), eluting with EtOAc (2 L) and then with 20% IPA/EtOAc(2 L). The IPA/EtOAc fraction is concentrated to give a residue, whichis dried under vacuum at room temperature for 1 hour to give the titlecompound (42.1 g, 88% yield, 88% purity by mass) as a pale brown foam.

The foam is combined with another lot of similar purity and the combinedmaterial (46.0 g, 92.3 mmol) is combined with MTBE (230 mL) and heptane(230 mL) at room temperature. The mixture is stirred vigorously in a 45°C. heating block for 1 hour, then at room temperature for 30 minutes andthen is filtered. The filtered solid is combined with EtOAc (400 mL) andSiliaMetS Thiol (40 g) is added. The mixture is agitated on a rotaryevaporator at room temperature for 1 hour, then is filtered. Thefiltrate is concentrated to give a residue, which is combined with 25%EtOAc/heptane (400 mL) and the mixture is stirred vigorously in a 50° C.heating block for 1 hour, then at room temperature for 10 minutes, thenis filtered, keeping aside the first batch of filtrate. The filteredsolid is combined with 35% EtOAc/heptane (400 mL) and the mixture isstirred vigorously in a 50° C. heating block for 1 hour, then at roomtemperature for 10 minutes, then is filtered, keeping aside the secondbatch of filtrate. The filtered solid is combined with EtOAc (500 mL)and 15% aq. KHSO₄ solution (500 mL). The mixture is stirred vigorouslyat room temperature for 15 minutes, then is transferred to a separatingfunnel and the layers are separated, leaving a rag layer in theorganics. The organic layer is further extracted with 15% aq. KHSO₄solution (100 mL), leaving a rag layer in the organics. The rag layer isremoved from the organics and is diluted with CH₂Cl₂ (100 mL) and 15%aq. KHSO₄ solution (100 mL) and the layers are separated. The combinedaqueous layers are stirred in an ice-water bath and solid Na₂CO₃ (100 g)is added portionwise over 5 minutes with stirring (pH measured as 10 bypH paper). The mixture is extracted with CH₂Cl₂ (2×500 mL) and thecombined organics are dried over Na₂SO₄ and concentrated to give thefirst batch of crude product. The first and second batches of filtratesfrom the filtrations are combined and concentrated, then the residue iscombined with EtOAc (100 mL) and 15% aq. KHSO₄ solution (100 mL). Themixture is stirred vigorously at room temperature for 15 minutes, thenis transferred to a separating funnel and the layers are separated. Theaqueous layer is stirred in an ice-water bath and solid Na₂CO₃ (15 g) isadded portionwise over 5 minutes with stirring (pH measured as 10 by pHpaper). The mixture is extracted with CH₂Cl₂ (2×100 mL) and the combinedorganics are dried over Na₂SO₄ and concentrated to give a residue whichis combined with 25% EtOAc/heptane (80 mL) and the mixture is stirredvigorously in a 50° C. heating block for 30 minutes, then at roomtemperature for 10 minutes, then is filtered to give the second batch ofcrude product. The two batches of crude product are combined with 25%EtOAc/heptane (400 mL) and the mixture is stirred vigorously in a 50° C.heating block for 30 minutes, then at room temperature for 10 minutes,then is filtered. The filtered solid is dried under vacuum at roomtemperature 3 days to provide the final title compound (37.4 g, 90%yield) as a white solid. ES/MS m/z: 441 (M+H). Optical rotation[α]D₂₀=+104.0° (c=0.2, MeOH).

Example 31-[6-[(3R,5S)-1-[(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)methyl]-5-methyl-pyrrolidin-3-yl]oxy-1,3-dihydropyrrolo[3,4-c]pyridin-2-yl]ethanone

Scheme 4, step D: To a scintillation vial containing6-fluoro-2-methyl-1.3-benzothiazole-5-carbaldehyde (0.071 g, 0.363 mmol)and1-[6-[(3R,5S)-5-methylpyrrolidin-3-yl]oxy-1,3-dihydropyrrolo[3,4-c]pyridin-2-yl]ethanone;hydrochloride(0.1 g, 0.335 mmol) in dichloromethane (3.5 mL) is addedN,N-diisopropylethylamine (0.175 mL, 1 mmol). The solution is stirred atroom temperature and sodium triacetoxyborohydride (0.220 g, 1.038 mmol)is added. The solution is stirred at room temperature for 20 hours. Thereaction is slowly quenched with saturated aqueous sodium bicarbonate (3mL). The aqueous layer is extracted with dichloromethane (3×5 mL). Thecombined organic phase is dried over magnesium sulfate, filtered, andconcentrated under reduced pressure. The residue is purified by reversephase HPLC (solvent A: aqueous 10 mM ammonium bicarbonate pH=10/5% MeOH,solvent B: acetonitrile, Phenomenex Kinetex EVO C18, 100×30 mm column,50° C. column heater) to give1-[6-[(3R,5S)-1-[(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)methyl]-5-methyl-pyrrolidin-3-yl]oxy-1,3-dihydropyrrolo[3,4-c]pyridin-2-yl]ethanone(0.089 g, 0.203 mmol, 56% yield). ES/MS m/z: 441 (M+H). [α]_(D)²⁰=+22.5° (c=0.2, MeOH).

Example 41-[3-[(3R,5S)-1-[(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)methyl]-5-methyl-pyrrolidin-3-yl]oxy-5,7-dihydropyrrolo[3,4-b]pyridin-6-yl]ethanone

Scheme 5, step D: To a solution of6-fluoro-2-methyl-1.3-benzothiazole-5-carbaldehyde (0.057 g, 0.292 mmol)and1-[3-[(3R,5S)-5-methylpyrrolidin-3-yl]oxy-5,7-dihydropyrrolo[3,4-b]pyridin-6-yl]ethanone;hydrochloride(0.089 g, 0.299 mmol) in dichlormethane (3 mL) is addedN,N-diisopropylethylamine (0.15 mL, 0.86 mmol). The solution is stirredat room temperature and sodium triacetoxyborohydride (0.188 g, 0.877mmol) is added. The solution is stirred at room temperature for 23hours. The reaction is slowly quenched with saturated aqueous sodiumbicarbonate (5 mL). The aqueous layer is extracted with dichloromethane(3×5 mL). The combined organic phase is dried over magnesium sulfate,filtered, and concentrated under reduced pressure. The residue ispurified by reverse phase HPLC (solvent A: aqueous 10 mM ammoniumbicarbonate pH=10/5% MeOH, solvent B: acetonitrile, Phenomenex KinetexEVO C18, 100×30 mm column, 50° C. column heater) to give1-[3-[(3R,5S)-1-[(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)methyl]-5-methyl-pyrrolidin-3-yl]oxy-5,7-dihydropyrrolo[3,4-b]pyridin-6-yl]ethanone(0.055 g, 0.125 mmol, 43% yield). MS m/z: 441 (M+H). [α]_(D) ²⁰=+50.7°(c=0.2, MeOH).

Example 51-[2-[(3R,5S)-1-[(1S)-1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethyl]-5-methyl-pyrrolidin-3-yl]oxy-5,7-dihydropyrrolo[3,4-d]pyrimidin-6-yl]ethanone

Scheme 3, step D: To a solution of1-(2-(((3R,5S)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidin-6-yl)ethan-1-onehydrochloride (0.165 g, 0.552 mmol) in acetonitrile (4.0 mL) is added5-[(1R)-1-chloroethyl]-6-fluoro-2-methyl-1,3-benzothiazole (0.097 g,0.422 mmol) and cesium carbonate (1.4 g, 4.3 mmol). The suspension isstirred at 68° C. for 21 h. The crude reaction is cooled to roomtemperature and filtered through celite. The filtrate is concentratedand purified via reverse phase chromatography on a Phenomenex KinetexEVO C18 column with aqueous 0.1% formic acid:MeCN as the mobile phase.This material is further purified on a Chiralcel OD-H column with 40%MeOH(0.2% IPAm)/CO₂ as the mobile phase to give1-(2-(((3R,5S)-1-((S)-1-(6-fluoro-2-methylbenzo[d]thiazol-5-yl)ethyl)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-d]pyrimidin-6-yl)ethan-1-one(0.050 g, 0.110 mmol, 26% yield). MS m/z: 456 (M+H). [α]_(D) ²⁰=−13.8°(c=0.2, MeOH).

Example 61-[2-[(3R,5S)-1-[(1S)-1-(6-fluoro-2-methyl-1,3-benzothiazol-5-yl)ethyl]-5-methyl-pyrrolidin-3-yl]oxy-5,7-dihydropyrrolo[3,4-b]pyridin-6-yl]ethanone

Scheme 3, step D: To a solution of1-(2-(((3R,5S)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-b]pyridin-6-yl)ethan-1-onehydrochloride (0.192 g, 0.644 mmol) in acetonitrile (5.0 mL) is added5-[(1R)-1-chloroethyl]-6-fluoro-2-methyl-1,3-benzothiazole (0.104 g,0.452 mmol) and cesium carbonate (1.56 g, 4.79 mmol). The suspension isstirred at 65° C. for 17 h. The crude reaction is cooled to roomtemperature and filtered through celite. The filtrate is concentratedand purified via flash chromatography (silica gel) eluting withhexanes:(3:1 acetone:DCM) [60:40 to 0:100]. This material is furtherpurified on a Chiralpak AD-H column with 40% MeOH(0.2% IPAm)/CO₂ as themobile phase to give1-(2-(((3R,5S)-1-((S)-1-(6-fluoro-2-methylbenzo[d]thiazol-5-yl)ethyl)-5-methylpyrrolidin-3-yl)oxy)-5,7-dihydro-6H-pyrrolo[3,4-b]pyridin-6-yl)ethan-1-one(0.033 g, 0.073 mmol, 16% yield). MS m/z: 455 (M+H). [α]_(D) ²⁰=+19.5°(c=0.2, MeOH).

In Vitro Human OGA Enzyme Assay Generation of OGA Enzyme

The nucleotide sequence encoding full-length humanO-GlcNAc-β-N-acetylglucosaminidase (NM_012215) is inserted intopFastBac1 (Invitrogen) vector with an N-terminal poly-histidine (HIS)tag. Baculovirus generation is carried out according to the Bac-to-BacBaculovirus Expression system (Invitrogen) protocol. Sf9 cells areinfected at 1.5×10⁶ cells/mL using 10 mL of P1 virus per Liter ofculture and incubated at 28° C. for 48 hrs. Cells are spun down, rinsedwith PBS and the pellets stored at −80° C. The above OGA protein(His-OGA) is purified as follows: 4 L of cells are lysed in 200 mL ofbuffer containing 50 mM Tris, pH 8.0, 300 mM NaCl, 10% glycerol, 10 mMimidazole, 1 mM dithiothreitol (DTT), 0.1% Triton™ X-100, 4 tablets ofprotease inhibitors (complete EDTA-Free, Roche) for 45 min at 4° C. Thiscell lysate is then spun for 40 min at 16500 rpm at 4° C., andsupernatant incubated with 6 mL of Ni-NTA resin (nickel-nitrilotriaceticacid) for 2 h at 4° C.

Resin is then packed onto column and washed with 50 mM Tris, pH 8.0, 300mM NaCl, 10% glycerol, 10 mM imidazole, 0.1% Triton™ X-100, 1 mM DTT,followed by 50 mM Tris, pH 8.0, 150 mM NaCl, 10 mM imidazole, 10%glycerol, 1 mM DTT. The proteins are eluted with 50 mM Tris, pH 8.0, 150mM NaCl, 300 mM imidazole, 10% glycerol, 1 mM DTT. Pooled His-OGAcontaining fractions are concentrated to 6 ml and loaded onto Superdex75(16/60). The protein is eluted with 50 mM Tris, pH 8.0, 150 mM NaCl, 10%glycerol, 2 mM DTT. Fractions containing His-OGA are pooled and proteinconcentration measured with BCA (Bradford Colorimetric Assay).

OGA Enzyme Assay

The OGA enzyme catalyses the removal of O-GlcNAc from nucleocytoplasmicproteins. To measure this activity Fluoresceindi-N-acetyl-β-N-acetyl-D-glucosaminide (FD-GlcNAc, Kim, Eun Ju; Kang,Dae Ook; Love, Dona C.; Hanover, John A. Carbohydrate Research (2006),341(8), 971-982) is used as a substrate at a final concentration of 6.7μM. This fluorogenic substrate becomes fluorescent upon cleavage by OGA,so that the enzyme activity can be measured by the increase influorescence detected at 535 nm (excitation at 485 nm).

The assay buffer is prepared to give a final concentration of 50 mMH₂NaPO₃—HNa₂PO₃, 0.01% bovine serum albumin and 0.01% Triton™ X-100 inwater, at pH 7. Compounds to be tested are diluted in pure dimethylsulfoxide (DMSO) using ten point concentration response curves. Maximalcompound concentration in the reaction mixture is 30 or 1 μM. Compoundsat the appropriate concentration are pre-incubated with OGA enzyme for30 minutes before the reaction is started by the addition of substrate.The final enzyme concentration is 3.24 nM or 0.5 nM, for the 30 or 1 μMmaximal compound concentration, respectively. Reactions are allowed toproceed for 60 min at room temperature. Then, without stopping thereaction, fluorescence is read. IC₅₀ values are calculated by plottingthe normalized data vs. log of the compound and fitting the data using afour parameter logistic equation.

The compounds of Examples 1 through 6 were tested essentially asdescribed above.

TABLE 1 Example IC₅₀ (nM) 1 0.465 ± 0.224 (n = 5) 2 0.214 ± 0.037 (n =4) 3 0.782 ± 0.087 (n = 3) 4 0.592 ± 0.068 (n = 2) 5 0.495 ± 0.109 (n =3) 6 0.385 ± 0.088 (n = 3)

The results in Table 1 demonstrate that the compounds of Examples 1through 6 inhibit OGA enzyme activity in vitro.

We claim:
 1. A compound of the formula:

wherein R is hydrogen or methyl; and Z is:

or a pharmaceutically acceptable salt thereof.
 2. The compound accordingto claim 1 wherein the methyl at position 5 on the pyrrolidine ring isin the cis configuration relative to the oxygen at position 3:

or a pharmaceutically acceptable salt thereof.
 3. The compound accordingto claim 2 wherein R is methyl; or a pharmaceutically acceptable saltthereof.
 4. The compound according to claim 2 wherein R is hydrogen; ora pharmaceutically acceptable salt thereof.
 5. The compound according toclaim 3 wherein R is methyl in the (S)-configuration; or apharmaceutically acceptable salt thereof.
 6. The compound according toclaim 3 wherein R is methyl in the (R)-configuration; or apharmaceutically acceptable salt thereof.
 7. The compound according toclaim 3 wherein Z is:

or a pharmaceutically acceptable salt thereof.
 8. The compound accordingto claim 3 wherein Z is:

or a pharmaceutically acceptable salt thereof.
 9. The compound accordingto claim 4 wherein Z is:

or a pharmaceutically acceptable salt thereof.
 10. The compoundaccording to claim 4 wherein Z is:

or a pharmaceutically acceptable salt thereof.
 11. The compoundaccording to claim 1 wherein the compound is:

or a pharmaceutically acceptable salt thereof.
 12. The compoundaccording to claim 1 wherein the compound is:

or a pharmaceutically acceptable salt thereof.
 13. The compoundaccording to claim 1 wherein the compound is:

or a pharmaceutically acceptable salt thereof.
 14. The compoundaccording to claim 1 wherein the compound is:

or a pharmaceutically acceptable salt thereof.
 15. The compoundaccording to claim 1 wherein the compound is:

or a pharmaceutically acceptable salt thereof.
 16. The compoundaccording to claim 1 wherein the compound is:

or a pharmaceutically acceptable salt thereof.
 17. A method of treatingAlzheimer's disease in a patient, comprising administering to a patientin need of such treatment an effective amount of a compound of claim 1,or a pharmaceutically acceptable salt thereof.
 18. A method ofpreventing the progression of mild cognitive impairment to Alzheimer'sdisease in a patient, comprising administering to a patient in need ofsuch treatment an effective amount of a compound of claim 1, or apharmaceutically acceptable salt thereof.
 19. A method of treatingprogressive supranuclear palsy in a patient, comprising administering toa patient in need of such treatment an effective amount of a compound ofclaim 1, or a pharmaceutically acceptable salt thereof.
 20. Apharmaceutical composition, comprising a compound or a pharmaceuticallyacceptable salt thereof according to claim 1 with one or morepharmaceutically acceptable carriers, diluents, or excipients.